Health

An anomaly, by definition, is something that different from the norm, this is something specific, special, abnormal, which is difficult to classify. In human biology, an anomaly is a genetic difference or something that cannot be explained.

Despite the fact that people in general have similar traits in terms of biology, sometimes scientists encounter a number of oddities that I would like to talk about.

Sexual Deviations

One of the strangest human features associated with biology can be called sexual deviations that are found in some individuals. These deviations include strange behavior and strange sexual desires that are different from the norm.

For some reason, some people have strange sexual stimuli which science cannot yet explain. One of the most famous such anomalies is exhibitionism, which consists in the demonstration of the genitals in public places.

Some scientists believe that this is a deviation is not innate and is acquired by a person in society, others are sure that this is a biological problem. Interestingly, most of the sexual anomalies are seen in men.

Paraphilia

In the 1920s, an Austrian psychiatrist Wilhelm Stekel introduced the term "paraphilia" to describe an abnormal sexual attraction to objects, situations, or persons that results in suffering and serious problems.

It is not known exactly how many different types of paraphilia are there, according to one source, there are 549 of them. Some activities related to sexual deviance are punishable by law and are not considered a disease. For example, pedophilia.

Interesting fact: Before 1974 homosexuality was included in the list of diseases associated with sexuality.

The influence of the sun on man

Soviet scientist Alexander Chizhevsky considered the founder of cosmic natural science, he was the first to explore the impact of solar energy on the Earth and its inhabitants. He found evidence that the Sun can cause various terrestrial phenomena. He connected the 11-year cycle of the Sun with climate change and mass activity.

Chizhevsky wrote that negative ionization in the atmosphere has a direct effect on human sensitivity and the behavior of the masses. He based this theory on historical data and statistics. He believed that the entire history of mankind falls under the influence 11-year cycle of solar activity.

Scientist studied historical events 72 countries from 500 BC to 1922, marking turbulent times such as warriors, revolutions, riots, expeditions, and migrations, and also looked at how many people took part in these events. It turned out that 80 percent the most significant historical events occurred precisely at the maximum solar activity.

These data were repeatedly checked by scientists after Chizhevsky, and again evidence of the influence of the Sun on humans was found. Solar flares have been found to affect the central nervous system, brain activity (including balance), and behavior and emotional responses.

Magnetic storms

Solar flares cause on Earth magnetic storms, which cause people to become more nervous, restless, anxious, confused, irritable, lethargic, tired, exhausted. Some people report experiencing prolonged headaches and intracranial pressure. Others report severe bouts of insomnia during peak solar activity.

Interesting fact: During from 1948 to 1997 Institute of Problems of Industrial Ecology of the North in Russia found that geomagnetic activity had three seasonal maxima, which caused an increase in anxiety, depression, bipolar disorder, and an increase in the number of suicides in the city of Kirovsk. We've just passed through solar maximum. in February 2013.

Left handed and right handed

In humans, the dominance of one hand over the other is associated with uneven distribution of fine motor skills. The reason why we cannot do everyday tasks with different hands in the same way is not yet known.

Obviously, there are more right-handers than left-handers ( 70-90 percent of all people on the planet). The percentage of right-handed people among primitive peoples is less. Over the past 25 years, research has shown that Left-handers have many more health risks than right-handers.

Research has also shown that left-handed people have a harder time developing language skills and often experience learning difficulties, they are more likely to have mental retardation. Among lefties there is also a fairly high percentage of sufferers dyslexia- inability to read. However, very often among left-handed people they meet gifted mathematicians and musicians. Sports abilities of left-handed people are lower, on average they have lower growth and also they thinner than righties.

Studies show that left-handed people tend to have fewer children and also have a shorter life expectancy. In 1991 one study published in the journal Psychological Bulletin, compared left-handers and right-handers among athletes playing basketball and cricket. It turned out that lefties die before righties.

Another 2007 study found that left-handed women died earlier than right-handed women. Also, the former were much more likely to have cases of rectal cancer, heart and vascular diseases.

It has also been confirmed that left-handed people are more likely to have depression, drug addiction, bedwetting, sleep disorders, autoimmune diseases, they are more likely to be born prematurely and more prone to suicide. There are suggestions that hormonal imbalance in the mother's body during pregnancy may have an impact on the birth of a left-handed child.

Interesting fact: Although scientists have not yet discovered a special set of left-handed genes, it is known that left-handers usually appear in families where one of the relatives already has the same anomaly.

Features of the respiratory system

nasal cycle- a biological anomaly that occurs in about 80 percent of the world's population. In these people, the breath switches from one nostril to the other. From a physiological point of view, a person has two nostrils that must work together to provide constant humidification, filtration and heating of the air that enters the lungs.

The nostrils are separated by a thin wall of cartilage called nasal septum. The two nasal cavities join at the throat to form one tunnel leading to the lungs.

With a nasal cycle that lasts an average 2.5 hours the cavernous tissue swells in one nostril, blocking it (not completely). At the same time, the tissue of the other nostril contracts, opening up for breathing. Thus, one nostril constantly accounts for 85 percent breath.

For a long time, scientists could not understand why the nasal cycle occurs, but recent studies have shown that switching from one nostril to another improves the sense of smell and helps prevent dryness and infections in the nose. It remains unclear why 20 percent of people do not have a nasal cycle.

Interesting fact: It has been observed that if you lie on one side of the body, through 12-15 minutes the cavernous tissue of the nostrils on this side of your body will begin to swell until you roll over to the other side. It is probably the nasal cycle that makes a person roll over in your sleep all the time.

intraanesthetic awakening

It is not yet clear why some people less sensitive to anesthesia, than others. For most of us, anesthesia or anesthesia causes loss of consciousness, but some patients do not fall asleep. Those who remain in the creation may feel pressure around the wound during surgery, feel hungry, hear the voices of doctors, and find it difficult to breathe.

If anesthesia does not work, the person may experience pain, panic, and about 70 percent these people experience prolonged symptoms, either physical or neurological.

Sometimes with anesthesia, a person remains conscious while they receive insufficient amount of general anesthetic, or the patient is in the intensive care unit and he is paralyzed. Also, often anesthesia does not work for those who are connected to the life support system.

People who remain conscious during anesthesia may experience severe injury. Studies have shown that anesthesia does not work one or two people out of a thousand patients.

A large number of genetic abnormalities may affect how quickly patients fall asleep during anesthesia. Women usually need a larger dose of anesthetic than men. The exact reason for this is not yet clear, but there are suggestions that a woman usually consumes less alcohol, has different hormones and a different distribution of body fat.

Interesting fact: Studies have shown that red-haired people require a large dose of anesthetic, they are often resistant to local painkillers like novocaine. It is believed that redheads are more sensitive to pain due to gene mutation (MC1R) which affects hair color.

Mongolian spot

Mongolian spot is an irregularly shaped bluish birthmark in infants that occurs on the skin in the sacrum, sometimes the thighs and buttocks, and is mainly characteristic of children from Asia, Polynesia, East Africa and Native Americans. These spots were discovered by scientists Erwin Balz after a deep study of the Mongols, hence the name.

Usually these spots are bluish tint and somewhat reminiscent of bruises, sometimes they can be dark brown. Mongolian spots usually disappear 3-5 years after birth, and by puberty they remain in units. Mostly these spots are observed in infants. East Asian groups, but can be found among the peoples of other areas.

The color of the Mongolian spots is associated with melanocytes, cells that contain melanin. In humans, melanin plays an important role in skin color. People whose ancestors lived for a long time in areas near the equator have more pigment eumelanin.

The appearance of Mongolian spots does not depend on gender. In some cases, if people do not know what Mongolian spots are, they may confuse them with bruises, which may raise suspicions about the treatment of children. Fortunately Mongolian spots harmless to humans.

Interesting fact: Mongolian spots and hair color are determined by the same body cells. As for eye color, with the development of the child, melanocytes, pigment cells, begin to slowly produce melanin, so immediately after birth, the eye color of all children is the same.

Communication between humans and animals

Science is still unable to understand exactly how humans and animals can communicate using non-verbal cues and sounds. The interaction between pets and their owners takes the form of a dialogue without the use of speech.

For example, a dog that is being scolded does not understand the language, but can biological signals, the position of the human body, his tone, body language, facial expressions. A person also understands a dog or other pets in the manner of their behavior and vocalization. For example, if an animal is under stress, this can be easily noticed.

Scholars debate whether human gestures such as smile, grimaces and eyebrow movement universal and whether they correspond to the signals of other primates. It is believed that the language of the human body includes involuntary reactions that are "read" by animals.

In some cases, a person has to imitate the behavior of animals in order to interact with them and gain trust. For example, cats have a mild reaction when they periodically open and close eyes feeling comfortable. A person subconsciously imitates such behavior in order to establish a good relationship with a cat. When you first meet a dog, you unconsciously stretch out your hand so that the animal can smell it. This allows the dog to get to know you and feel that you are not a threat.

Interesting fact: Studies have shown that people who have pets have a healthier heart, they are more active and less likely to feel despondency and stress. Pets help a person develop immunity against allergies, asthma, anxiety and other ailments.

identical twins

Identical or identical twins are born from one fertilized cell, which is divided into two or more parts. These children are always of the same sex, and they have almost the same set of genes, as well as the same DNA. Identical twins are more common than twins or fraternal twins. The latter develop simultaneously, but from different fertilized eggs.

Identical twins are natural clones of each other, and some parts of their body may be mirror reflection. For example, in many cases one of the twins is right-handed, the other is left-handed. It has also been reported that such twins may have different leg sizes.

Over the past century, twins have often been studied to identify genetic link between diseases and DNA. Since identical twins share the same genes, many experiments have been carried out to identify congenital or acquired features.

Not so long ago, identical twins helped determine that fainting in humans has a genetic basis.

In the criminal world, identical twins in some cases remain free if one of them commits a crime. It is impossible to prove exactly who it was. For example, in one famous case in 2009 the two twins were released because both had DNA linked to the theft of the jewels, but no evidence was found of which of them committed the crime.

Identical twins: similar, but not quite

Of course, identical twins have some differences in appearance from each other, but it is usually impossible to distinguish them at first glance. Studies have shown that identical twins are born one in 240 women giving birth.

Interesting fact: Elvis Presley had an identical twin brother Jesse Garon Presley, who was born 35 minutes before Elvis, but died immediately after birth.

Chimera

Chimera is an organism or tissue that contains at least two different sets of DNA, most often resulting from fusion of two different zygotes(fertilized eggs). Chimeras are obtained from at least 4 parental cells.

As an organism grows, each population of cells retains its characteristics, which result in a mixture of tissues. The probability of offspring of chimeras increases with in vitro fertilization. In 1953 in british medical journal The case of the birth of a chimera man was first described. The woman was found to have two different types of blood.

man chimera

In 2002 Englishwoman Lydia Fairchild did DNA analysis of her children to prove that the man named Jamie Townsend is their father. As a result of the analysis, it turned out that Townsend is indeed the father of the children, but Fairchild is not their mother at all. This news shocked Lydia, who had no doubt that the children were hers. The police arrested Fairchild and charged her with fraud and that she was involved in surrogacy.

Lawyer found an article in a magazine New England Journal of Medicine where a similar case was described. After multiple analyses, it turned out that Lydia is a chimera and that the children are indeed her own. Lydia had two different sets of DNA, she was cleared of all charges and entered into a special database.

Chimeras can be artificially obtained by selectively transplanting embryonic cells from one organism to another. Many chimera people do not have special features that distinguish them from ordinary people, while others do. For example, in 1998, doctors from University of Edinburgh received a patient who had both female and male reproductive organs. Most chimeras have minor features, such as different eye or hair colors.

Interesting fact: In 2007, scientists from University of Nevada created a sheep whose blood contained 15 percent human cells and 85 sheep cells. This experiment was an attempt to create a potential human-animal hybrid that could be used to produce cells or organs. Naturally, these studies raised a lot of noise and were called unethical. The US has passed a law banning experiments with chimeras.

Who can feel the Earth's magnetic field?

magnetic flair- the ability to sense the Earth's magnetic field to determine direction, latitude and location. They have such a flair bacteria, birds, fungi, insects, turtles, dolphins, lobsters, sharks, rays and many other animals. The mechanism that they use to perceive the magnetic field is unknown, but scientists have several hypotheses on this.

According to one theory, the ability to feel the magnetic field is associated with cryptochromes- a class of photosensitive proteins of plants and animals. Cryptochromes help some animals detect a magnetic field. According to another version, magnetic flair is obliged magnetic iron oxide.

It has been discovered that a person can also have a magnetic sense. Scientists have found magnetic bones in the human nose. Surprisingly, these bones, which contain iron oxide, have received very little study. A 2007 study suggested that low-frequency magnetic fields could trigger a response in the human brain.

A surprising discovery was also made: a magnetic field-sensitive protein was found in the human eye. cryptochrome-2. Scientists conducted a series of experiments, as a result of which it turned out that if this protein is injected into fruit flies, they develop ability to detect magnetic field. It is not yet known for sure whether this protein works the same way in humans as it does in animals.

Despite research into magnetic sensing, no one has yet been able to find sensitive receptor, which is responsible for the ability to feel the magnetic field. The problem is that research often uses stronger magnetic fields than the Earth's.

It is difficult to say exactly how the magnetic field of our planet affects life, but it is known for sure that animals feel its strength and angle, at which the field meets the surface.

Past research has shown that in addition to helping birds navigate in space, magnetic sense probably helps they perceive the world around them visually.

Interesting fact: After the discovery of cryptochrome-2 in the human eye, the question of the sixth sense of man was raised. This protein has been associated with the regulation of circadian rhythms, that is, the "biological clock" of a person.

Chimeras are called organisms or their parts, consisting of genetically heterogeneous tissues. For the first time, this term was used by the German botanist G. Winkler (1907) for plant forms obtained by merging nightshade and tomato. Later (1909) E. Baur, studying variegated pelargonium, found out the nature of chimeras. There are several types of bizarre organisms:

• Mosaic chimeras (hyperchimeras) - in them genetically different tissues form a thin mosaic;
• chimeras are vectorial - they have heterogeneous tissues located in large areas;
• periclinal chimeras - tissues with different genotypes lie in layers on top of each other;
• · mericlinal chimeras - their tissues consist of a mixture of sectorial and periclinal sections. Chimeras can arise as a result of plant grafting and under the influence of mutations in somatic cells. The components of chimeras may differ from each other in terms of nuclear genes, number of chromosomes, or plastid or mitochondrial genes. Bizarre organisms are often used in scientific research.

The principle of obtaining chimeras is reduced mainly to the isolation of two or more early embryos and their fusion. In the case when the genotype of the embryos used to create the chimera differs in a number of characteristics, it is possible to trace the fate of cells of both species. With the help of bizarre mice, for example, the question of the method of the emergence of multinuclear cells of striated muscles in the course of development was solved. The study of chimeric animals has solved many problems, and in the future, thanks to the application of this method, it will be possible to solve complex problems of genetics and embryology. Obtaining such embryos is carried out in many laboratories. The principle of obtaining chimeras is reduced mainly to the isolation of two or more early embryos and their fusion. In the case when the genotype of the embryos used to create the chimera differs in a number of characteristics, it is possible to trace the fate of both types of cells.

Two methods for obtaining chimeras: 1) aggregation - combining two or more morulae or blastocysts into one embryo; 2) injection - microinjection of cells of the intracellular mass of the donor blastocyst into the blastocoel of the recipient embryo. There are intraspecific and interspecific chimeras of laboratory animals and agricultural animals. In the offspring of chimeric animals, the parental genotype is not preserved, splitting occurs, and valuable genetic combinations are violated.

The development of genetic engineering has created a fundamentally new basis for constructing DNA sequences required by the researcher. Advances in experimental embryology have made it possible to develop methods for introducing such artificially created genes into the nuclei of spermatozoa or eggs. As a result, it became possible to obtain transgenic animals.

transgenic organisms

Transgenic refers to plants and animals that contain in their cells the gene of a foreign organism, which is included in the chromosomes. They are obtained using genetic engineering methods. Transgenic organisms can be of great importance in improving the efficiency of agriculture and in molecular biology research.

The first genetically modified organisms obtained using molecular biology methods appeared only in the 80s of the XX century. Scientists have managed to change the genome of plant cells, adding to them the necessary genes of other plants, animals, fish and even humans.

The first transgenic organism (mouse) was obtained by J. Gordon et al. in 1980. At the beginning of the 90s, the first commercial trials of genetically modified varieties of tobacco and tomatoes resistant to viruses were carried out in China. And in 1994, in the United States, for the first time, fruits of genetically modified tomatoes with a reduced ripening period entered the food distribution network.

In a number of experiments, it was found that mice developing from a zygote into which foreign DNA was introduced contain fragments of this DNA in their genome, and sometimes they also express foreign genes.

The purpose of creating transgenic organisms is to obtain an organism with new properties. The cells of a transgenic organism produce a protein whose gene has been introduced into the genome. The new protein can be produced by all cells in the body (non-specific expression of the new gene) or certain cell types (specific expression of the new gene).

The creation of transgenic organisms is used:

• - in a scientific experiment for the development of technology for creating transgenic organisms, for studying the role of certain genes and proteins and biological processes; transgenic organisms with marker genes have gained great importance in scientific experiment
• - in agriculture to obtain new varieties of plants and animal breeds;
• - in the biotechnological production of plasmids and proteins.

At present, a large number of strains of transgenic bacteria, lines of transgenic animals and plants have been obtained. Close in meaning and meaning to transgenic organisms are transgenic cell cultures. The key step in the technology of creating transgenic organisms is transfection - the introduction of DNA into the cells of the future transgenic organism.

If the hybrid DNA is introduced into a fertilized egg, transgenic organisms can be obtained that express the mutant gene and pass it on to offspring. The genetic transformation of animals makes it possible to establish the role of individual genes and their protein products both in the regulation of the activity of other genes and in various pathological processes. With the help of genetic engineering, lines of animals resistant to viral diseases, as well as animal breeds with traits useful for humans, have been created.

From school, we know that the chimera is a mythical monster. Whatever character traits myths and fairy tales endowed him with, it looked repulsive.

What is a chimera

From the point of view of biologists, a chimera is an organism consisting of cells with different genes. Chimerism manifests itself in plants, animals and even people, including twins. Genetic mutations, often occurring without human intervention, have led to the following animals.

Venus cats

Her unusual appearance almost left the animal in the shelter forever. Experts believe that the murka has become a clear example of chimerism, which resulted in eyes of different colors and two-tone fur.

Frank-and-Louis

It is difficult to understand that this is one head for two animals or two heads for one cat. The genetic mutation that affected the unfortunate is called "Janus syndrome", and this is not the first cat with a similar problem.

Piglet Rudy

In the animal shelter, he received a middle name - Deuce. The animal had two ears, three eyes and two snouts, located on fully formed skulls, but only one neck. The shelter staff bought the creature from the owners so that it would not become a valuable exhibit in the menagerie. The baby did not live long.

Chimera fish

Their characteristic feature is called a valky body, slightly compressed on the sides and gradually fading away to the tail. The latter often looks like a long cord. The paired fins of such individuals have thin, flexible, but rather fleshy lobes.

Tiger Kenny

He was born in captivity not only with a white skin, but also with a strange muzzle. The animal could not close its jaws, and its brain was hypertrophied. His life ended in 2008. The cause of death was cancer.

I found out the nature of this phenomenon.

Chimeras may occur

• as a result of plant grafting
• under the influence of mutations in somatic cells.

Periclinal chimeras are:

• diplochlamides (eg pelargonium with white-leafed leaves)
• haplochlamydes (for example, chlorophytum with white-edged leaves)

The interaction between the components of chimeras, and the transition of various substances from one component to another, can lead to various developmental anomalies and sometimes to sterility of the chimera.

In the practice of gardeners, chimeras that arose by chance as a result of vaccinations (the so-called variegation) are reproduced by vegetative propagation again from generation to generation (for example, chimeras between purple broom and golden rain - the so-called Adam's broom, chimeras between orange and lemon) . Researchers apply various chimeras between medlar and hawthorn.

Chimeras in zoology

Chimera mouse (right).

Chimeras can form from four gametes (the result of the union of two fertilized eggs or embryos in the early stages of development into one embryo).

Chimerism in animals can be both the result of the individual development of the organism (ontogenesis), and the result of transplantation of an organ, tissue (for example, bone marrow or blood transfusion). In heterozygous (non-identical) twins, chimerism can result from the union of blood vessels (anastomoses). Chimeras can often produce offspring, and the type of offspring depends on which cell line the gametes developed from.

In the 1980s, an interspecific chimera of a sheep and a goat was obtained artificially.

Fetal and maternal microchimerisms

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See what "Chimera (biology)" is in other dictionaries:

The Chimera of Arezzo is an Etruscan bronze sculpture. Museum of Archeology, Florence, Italy Chimera (Greek Χίμαιρα, "goat") in Greek mythology, a monster with the head and neck of a lion, the body of a goat, the tail of a dragon; offspring of Typhon and Echidna ... Wikipedia

This term has other meanings, see Chimera (meanings). The Chimera of Arezzo is an Etruscan bronze sculpture. Museum of Archeology, Florence ... Wikipedia

Ornithopter Chimera ... Wikipedia

A hybrid of a horse and a zebra A hybrid (from lat. hibrida, hybrida hybrid) is an organism (cell) obtained as a result of crossing genetically different forms. The concept of a hybrid is especially common in botany, but is also used in zoology. In ... Wikipedia

During pregnancy, two-way traffic of immune cells can occur across the placenta. Exchanged cells can divide and establish long-term cell lines that are immunologically active even decades after birth. ... ... Wikipedia

Kidney grafting scheme: 1 scion bud is removed along with the underlying tissues; 2 4 the bud is inserted into a T-shaped incision on the stem of the stock and fixed there, 5 the bud forms a shoot. Vegetative hybridization is one of the central concepts ... ... Wikipedia

Kidney grafting scheme: 1 scion bud is removed along with the underlying tissues; 2 4 the bud is inserted into a T-shaped incision on the stem of the stock and fixed there, 5 the bud forms a shoot. Vegetative hybridization is one of the central concepts ... ... Wikipedia

Kidney grafting scheme: 1 scion bud is removed along with the underlying tissues; 2 4 the bud is inserted into a T-shaped incision on the stem of the stock and fixed there, 5 the bud forms a shoot. Vegetative hybridization is one of the central concepts ... ... Wikipedia

This article lacks links to sources of information. Information must be verifiable, otherwise it may be questioned and removed. You can ... Wikipedia

A resident of the United States, Lydia Fairchild, was in for an unpleasant surprise when, after a divorce, she applied for social benefits. Her husband had to confirm paternity by DNA analysis - and the latter showed that Lydia was not the mother of two common children (and at the same time the third, with whom she was pregnant at that time). At first, there was an assumption that the cause was a tissue transplant or a blood transfusion, but neither the woman nor the children were exposed.

The state filed a fraud lawsuit. The situation was saved by Mrs. Fairchild's lawyer - he provided the court with an article from the New England Journal of Medicine:

Boston teacher Karen Keegan, 52, needed a kidney transplant. Three of her sons agreed to be donors, but during genetic analysis it turned out that two of them are not relatives of their own mother! Research has established a lot of interesting facts: in particular, it turned out that Karen had a twin sister, who merged with the surviving embryo at an early stage of embryonic development. The Boston teacher turned out to be a chimera - a creature in whose body there are, without interfering with each other, tissues with different sets of genes.

In the precedent with Mrs. Fairchild, everything turned out to be even more complicated - the DNA of Lydia's children proved only a relationship with their grandmother, Mrs. Fairchild's mother. It was possible to figure it out only thanks to the analysis of the hair, and the hair on the head and pubic hair of the woman contained different genetic material. Mrs. Fairchild came out unscathed, and in 2006, the program “My Twin in Me” was dedicated to her story.

About forty cases of chimerism have been officially recorded, but in fact there are many more. With a high probability, the famous maniac Chikatilo was a chimera, whose data on blood type and sperm did not match. Sometimes chimerism accidentally pops up when trying to in vitro fertilization or artificial insemination: scientists from Germany described a patient in whom 99% of the cells in the body contained the female chromosome set XX and 1% - male, XY. As it turned out, her twin brother died at birth, but his cells lived in her sister's body.

And these are just cases reported to the general medical community.

Paws, wings and tail

The term "chimera" is taken from Greek mythology - it is a "composite" monster with a goat's body, a lion's head, a snake's tail, etc. It was generated by ugly monsters - a half-woman half-snake Echidna and the giant Typhon, killed, according to one version, by a hero Bellerophon. In biology, a chimera, as already mentioned, is a creature with heterogeneous genetic material coexisting in one organism. The term was first introduced in 1907 by the German botanist Hans Winkler, who called chimeras plants obtained by grafting nightshade onto a tomato stalk. Another botanist, Erwin Baur, explained the nature of the phenomenon. And the first "compound" animal was constructed in 1984 - an artificial "mosaic" of a sheep and a goat, a cub of four parents, some of whose cells contained a sheep genome, and some - a goat.

Chimerism in plants is the result of natural mutations or grafting, when a branch of a plant of one species is planted on the trunk of another. Luther Burbank's experiments with the famous Russet Burbank, a potato variety that now accounts for up to 50% of the potato crop in the United States of America, seedless plums, and pineapple-scented quince were mostly Frankenstein creations in the plant world.

The famous Michurin did the same, who studied in detail how the rootstock (a young plant on which someone else's cutting is planted) affects the yield, viability and other properties of the scion. The graft-versus-host disease that makes organ transplants so dangerous in humans and animals is, in general, unusual for plants. The only difficulty is that green chimeras, as a rule, do not pass on their qualities by inheritance, they have to be propagated by vegetative means.

Chimerism in mammals can be the result of several processes, both natural and artificial. The first is the so-called tetragametic chimerism, when two eggs merge together, each of which is fertilized by its own sperm, or two embryos in the early stages of development, as a result of which different organs or cells of such an organism contain a different chromosome set. Stories with the "absorbed twin" are a typical example of such chimerism.

The second is microchimerism. Infant cells can enter the mother's circulatory system and take root in her tissues (fetal microchimerism). For example, fetal immune cells can (at least for several years) cure a mother of rheumatoid arthritis, help restore heart muscle after heart failure that developed during pregnancy, or increase the mother's resistance to cancer. Conversely, maternal cells cross the placental barrier to the fetus (maternal microchimerism). Not without his help, the system of innate immunity is formed: the immune system of the fetus is “trained” to resist diseases, immunity to which the mother has developed. The flip side of this coin is that a child in the womb can become a victim of her own diseases. In particular, an autoimmune disease such as neonatal lupus is often found in children whose mothers suffer from systemic lupus erythematosus.

The third variant of natural chimerism is “twin”, when, due to the fusion of blood vessels, heterozygous twins transfer their cells to each other (not with the same, as in homozygous, but with the same as in siblings, differing sets of genes). This is how the German patient mentioned above became a chimera.

The next variant of chimerism is post-transplantation, when after a blood transfusion or organ transplant in the human body, one's own cells coexist with the donor's cells. It is very rare, but it happens that the donor's cells are completely "integrated" into the recipient's body - for example, a few years ago, after a liver transplant, an Australian girl had her blood type permanently changed.

The last option is a bone marrow transplant, in which doctors make every effort to make a chimera out of a patient and make the transplanted cells work instead of the host's.

The patient's own bone marrow is killed by irradiation and special preparations, donor hematopoietic cells are injected in its place and they wait. If the tests reveal donor chimerism, everyone is happy, the process is underway, and if transplant rejection is managed, there are chances for recovery. But the return of "native" cells means an early relapse of the disease.

Laboratory chimeras

The history of chimeric embryos began with Dr. Ray Owen's bulls and Dr. Peter Brian Medawar's chickens, thanks to which the mechanism of chimerization was developed.

Calves and chickens Owen first noticed that in twin calves, cells with heterogeneous genetic material perfectly coexist in the body, and the reason for this is the fusion of blood vessels. And Dr. Medawar first spliced ​​chicken eggs cut in the shell with "windows", then he set up experiments on introducing duck cell cultures into chicken embryos, then he began to connect the circulatory systems of chicken embryos and, finally, formulated the term "immunological tolerance" - the body's readiness to accept foreign cells. He was the first to transplant the embryos of mice from one pure line of embryonic cells to another, and then transplanted skin flaps to the surviving chimeras to demonstrate that the transplanted biomaterials retain the properties of the native organism and are not rejected. Scientists in Chicago and Liverpool have constructed chimeras of wood mice and house mice in laboratories by introducing additional genetic material into embryos at the blastocyst stage.

The mice turned out to be quite viable: more active than domestic mice, but less active than forest mice. In Russia, chicken chimeras were successfully grown - white leghorns with red tails of Rhodeland.

toy men

Another option for creating chimeras is the introduction of human DNA into an animal egg. The genetic material of cybrids - cell hybrids - is almost entirely human, they receive only mitochondrial DNA from an animal. True, attempts to bring hybrid embryos to the birth of chimeras at the present level of science are doomed to failure; besides, human cloning, and even more so the creation of human-animal chimeras, is legally prohibited in all developed countries. And there is no point in such complex experiments. Several dozen cybrid embryos, created for purely research purposes, were destroyed a few days after the start of egg division.

Doctors and homunculi

It took scientists about twenty years (since the first successful operation of Dr. Thomas) to learn how to select donors and recipients compatible for human leukocyte antigens - proteins, the mismatch of which triggers a cascade of molecular reactions leading to transplant rejection, and to fight rejection with the help of drugs, immunosuppressive. By 1990, about 4,000 bone marrow transplants had been performed, less than what is done in a year today. Now the five-year survival rate (in fact, recovery) for acute leukemia is 65%. Accordingly, it became possible to observe the unexpected effects of chimerism.

Doctors and relatives of the patients have long been ready for the fact that after transplantation the blood type, Rh factor and hair structure can change - but this is by no means all.

The fact that a bone marrow transplant can even cure AIDS is an accidental discovery, the luck of German doctors. About 1% of Europeans are known to be resistant to HIV. A 42-year-old American man with both lymphoma and AIDS underwent a bone marrow transplant to get rid of one of his illnesses. And unexpectedly for everyone (including doctors), he was healed of both - his donor turned out to be a carrier of a mutation that provides resistance to the virus, and transferred it to the recipient along with the bone marrow.

Know-how of the 21st century - developments in intrauterine cell therapy. Blood stem cells are injected into a fetus suffering from immunodeficiency, thalassemia, granulocytosis - and theoretically the child should be born healthy. In practice, it was possible to achieve an effect only in fetuses with immunodeficiency, in all other cases, even with minimal chimerism, the disease did not recede. Experiments on complex therapy are actively conducted on animals: first, the fetal immunity is “turned off”, and then a transplant is performed. But human experimentation is still a long way off.

Chimerism for good

Medicine put the possibilities of chimerism at its service even before this phenomenon was studied in its entirety. In 1940, the first attempt was made to transplant the bone marrow of his brother to a patient with aplastic anemia. In 1958, six Yugoslav physicists injured in the accident at a nuclear power plant were treated with a bone marrow transplant in Paris, five of them survived. In 1957, in the USA, Dr. Edward Thomas managed (after total body irradiation) to achieve engraftment in two children with leukemia. The children soon died, and after 10 years, of the 417 transplants performed by Thomas, only three were successful. In 1968, a completely successful transplant was carried out: a child with severe immunodeficiency was injected with the bone marrow of his brother. The patient recovered, becoming a chimera - instead of his own cells, blood in the body was produced by "brotherly". Edward Thomas received the Nobel Prize in Medicine in 1990.

edited news olqa.weles - 28-01-2012, 17:47